1. Field of the Invention
The present invention relates to a rolling train for rolling flat steel using universal stands having--instead of vertical rolls--adjustable support members for pairs of loose vertical rollers arranged in the areas of the stands.
2. Description of the Related Art
German Patent 36 35 440 discloses a universal stand in which different widths of a flat steel blank and the necessity of a clean processing of the edges of the blank are taken into consideration by arranging in front of and behind the horizontal rolls of the universal stand pairs of vertical rollers which are mounted in support yokes, wherein the support yokes are pivotable about vertical axes located centrally and at a distance from the common axis plane of the vertical rollers. This known arrangement, in which the vertical rollers are not driven, is supposed to make it possible to move the vertical rollers as closely as necessary to the roll gap of the horizontal rolls and to apply the necessary rolling pressure for working the edges of the flat steel blank without the danger of a deformation of the blank over the width thereof.
The universal stands of this type have in the past always been used in conventional universal beam rolling trains which were composed of a two-high reversing roughing stand with long roll body lengths of about 2.5 m and at least one universal stand reversing group and, more recently, a XH-tandem reversing group, and which made it possible to combine the rolling of flat steels with the production of sectional steel or beams.
The procedure of flat steel rolling in these trains has the following disadvantages:
There are limitations of the roughing rolling operation on the two-high reversing roughing stand with the long roll body lengths necessary for sectional steel rolling with respect to rolling force and rolling tolerances because of the substantial bending of the rolls. The necessary high pass numbers do not make it possible to carry out a combined operation with an appropriate slab/strand casting plant. The temperature conditions also limit the number of passes in the roughing stand and, thus, the achievable final thickness which must serve as the initial pass thickness for the following universal rolling and, therefore, requires more rolling work in the universal rolling step. The greater rolling thicknesses which are produced in the two-high reversing stand cannot be sufficiently edged during roughing rolling at the edges as would be desirable in wide flat steels or universal wide flat steels. Edging in the two-high reversing stand is only possible for such a time as the rolling thickness and rolling width permit it that the flat section is placed upright and an on-edge edging of the flat section is possible.